Thermoplastic Starch Blends Research Articles

Effects of LLDPE on Mechanical Properties, Degradation Performance, and Water Absorption of Thermoplastic Sago Starch Blends

The purpose of this study was to improve the mechanical and physical properties, degradation performance, and water absorption of a thermoplastic mixture of sago starch with the addition of Linear Low-Density Polyethylene (LLDPE). The method used is the grafting method where polyethylene is grafted onto Maleic Anhydride (LLDPE-g-MA). In this research, Thermoplastics Sago Starch (TPSS) was made with a mixture of Sago Starch (65%) and Glycerol (35%), added with water as a solution. Compatibilizer (PE-g-MA) was made by reacting LLDPE (88%) and Maleate Anhydride (9%) with an additional initiator of Benzoyl Peroxide (3%). The concentration of LLDPE varied from 10,15, 20, 25, and 30%. Substances were mixed into an internal mixer Thermo Haake Polydrive with a speed of 100

Biodegradable Poly (Butylene Adipate‐Co‐Terephthalate) and Thermoplastic Starch Sustainable Blends Modified by Epoxy‐Terminated Hyperbranched Polyester with Excellent Mechanical Properties and High Transparency

AbstractA kind of fully biodegradable poly (butylene adipate‐co‐terephthalate) (PBAT)/thermoplastic starch (TPS) blend is prepared by melt processing with epoxy‐terminated hyperbranched polymer (EHBP) as a modifier. The effect of EHBP on the performance of PBAT/TPS blends is investigated. The terminal epoxy group of EHBP can react with the hydroxyl and carboxyl groups of PBAT and TPS, which increases the compatibility of PBAT and TPS. Meanwhile, the formation of hydrogen bonds and chain entanglement increases the adhesion between PBAT and TPS, which improves the mechanical properties of the blends. When the content of EHBP is 3 phr, the elongation at break of TPS/PBAT/EHBP blends increases by 28.99% (from 260.32% to 335.79%) and the impact strength increases by 215.78% (from 9.38 to 29.62 kJ m−2). Scanning electron microscopy (SEM) images show that the compatibility of PBAT/TPS/EHBP blends gradually improves with the addition of EHBP. UV results show that the transparency of PBAT/TPS blends is greatly improved by the addition of EHBP, which also indicates the compatibility of PBAT and TPS is improved by the addition of EHBP. It provides an effective way to prepare PBAT blends with excellent properties through, an environmentally friendly and low‐cost processing method.

Melt flow Index (MFI) analysis of sago based thermoplastic starch blend with polypropylene and polyethylene

Melt flow Index (MFI) analysis of sago based thermoplastic starch blend with polypropylene and polyethylene

Biodegradable thermoplastic natural rubber based on natural rubber and thermoplastic starch blends

Biodegradable thermoplastic natural rubber based on natural rubber and thermoplastic starch blends

Reactive biodegradable extruded blends of thermoplastic starch and polyesters

Poly(butylene succinate) (PBS) and poly(butylene adipate co-terephthalate) (PBAT) are biodegradable polymers applied as alternative materials to non-biodegradable plastics. They have adequate mechanical properties to be used on an industrial scale, but their high cost is a limiting factor. Using thermoplastic starch (TPS) as the main component of the matrix is an alternative to producing low-cost materials. This work aimed to develop PBAT/PBS/TPS biodegradable films by blown extrusion, combining the most attractive properties of each polymer: the ductility of PBAT, the tensile strength of PBS, and the biodegradability and low cost of TPS. PBS/PBAT/TPS (20/10/70 wt%) sample achieved the best balance between hardness, ductility, and strength, with an elongation at break of 32%, a tensile strength of 6 MPa, and Young's modulus (YM) of 56 MPa. Citric acid acted as a multifunctional compound, increasing tensile strength and elongation at break and decreasing YM for all films. It increased the opacity and degree of crystallinity of the films but did not influence the color. FTIR did not indicate chemical reactions between the constituents, and the SEM showed higher compatibility between TPS/PBAT than with PBS. Our work proposed a well-known manufacturing process that allows scaling up the production of biodegradable films.

Photodegradation of biobased polymer blends in seawater: A major source of microplastics in the marine environment

IntroductionBiobased polymer blends have been recommended as an eco-friendly solution to abate plastic pollution in the environment. However, the formation of microplastics (MPs) by photodegradation of biobased polymer blends in the marine environment is still not well understood. In this study, we investigated the formation of MPs and the changes in the physicochemical properties of three types of biobased polymer blends after photodegradation in seawater.MethodsThe investigated materials included non-biodegradable polyethylene/ thermoplastic starch blends (PE/TPS) and polypropylene/thermoplastic starch blends (PP/TPS), as well as biodegradable polylactic acid/poly (butylene adipate-co-terephthalate)/thermoplastic starch blends (PLA/PBAT/TPS). The control groups were the corresponding neat polymers, including polyethylene (PE), polypropylene (PP), and polylactic acid (PLA).ResultsThe size distribution of the pristine and aged MPs indicated that the polymer blends were more likely to produce small-sized particles after photodegradation due to their poorer mechanical properties and lower resistance to UV irradiation than the neat polymers. Noticeable surface morphology alterations, including cracks, holes, and pits, were observed for polymer blends after photodegradation, while neat polymers were relatively resistant. After photodegradation, the attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR) spectrum of the polymer blends showed a significant decrease in the characteristic bands of thermoplastic starch (TPS), indicating depletion of their starch fractions. The C1s spectra of the polymer blends demonstrated that the aged MPs contained fewer -OH groups than the pristine MPs, further confirming the photodegradation of TPS. The molecular weight distribution curve of the polymer blends shifted significantly towards low molecular weight, suggesting the occurrence of chain scission during photodegradation. These results indicate that the polymer blends have a higher degree of photodegradation than neat polymers, and thereby generate more small-sized MPs than neat polymers. Photodegradation caused changes in the contact angle and surface charge of MPs derived from biobased polymer blends, which may affect the vector effects of MPs on any coexisting pollutants.DiscussionIn summary, polymer blends may pose a higher risk to the marine environment than neat polymers, and caution should be taken in promoting biobased polymer blends.

Supercritical CO2 Impregnation of Thymol in Thermoplastic Starch-Based Blends: Chemico-Physical Properties and Release Kinetics.

The aim of the present study was to investigate starch-based materials, prepared in an environmentally friendly way and from renewable resources, suitable for the development of biodegradable active food packaging. For this purpose, a bioactive compound (thymol) was incorporated into thermoplastic starch (TPS) and a TPS blend with poly (ε-caprolactone) (TPS–PCL) by the supercritical CO2 (scCO2) impregnation process. Impregnation experiments with scCO2 were carried out at a pressure of 30 MPa and temperatures in the range of 40–100 °C during 1 to 20 h. The structural, morphological, and thermal properties of the obtained materials were comprehensively evaluated. Bioactive component release kinetic studies were performed in water at 6 °C and 25 °C. It was shown that the scCO2 impregnation process could be successfully employed for thymol loading into TPS and TPS–PCL. The process was significantly influenced by the operating temperature and time as well as content of PCL. The samples showed a controlled release of thymol within seven days with a higher amount of released thymol from the TPS–PCL blend. The obtained materials are solvent-free and release the bioactive component in a controlled manner.

Effect of surfactant content on rheological, thermal, morphological and surface properties of thermoplastic starch (TPS) and polylactic acid (PLA) blends

Miscibility in biopolymeric blends is a critical process that requires evaluation of the effect of surfactants or coupling agents under conditions similar to processing. Different mixtures in the molten state of plasticized starch and polylactic acid in the presence of a surfactant (Tween 20) at different concentrations were studied. This allowed knowing the rheological, thermal and surface behavior of the mixtures. The results of the dynamic rheological analysis showed increases in viscosity in the presence of the surfactant, in which strong interactions were produced at high shear rates that reflect possible crosslinking between the polymer chains, in addition to intermolecular interactions that were evidenced in the infrared spectrum. Likewise, the storage and loss modulus showed transitions mainly from viscous to elastic typical for thermoplastics. The thermogravimetric analysis did not show significant changes between the mixtures. However, the calorimetric analysis showed changes in the crystallinity of the mixtures, the tensoactive promotes greater freedom of movement and rearrangements in the microstructure with decrease of interface between polymers, and less compaction of the material induced by the emulsion. Analysis derived from biopolymeric films against contact with water shows significant changes. Interaction with water in short times (in the order of minutes) according to the sessile drop technique, favors hydrophilicity by increasing the concentration of Tween 20. However, interaction with water for prolonged times (in the order of hours), shows that the absorption reaches saturation in samples a stabilization in the absorption is observed. The results demonstrate that the miscibility of PLA in AS was achieved in the presence of the tween, under conventional processing conditions. The stability of the different formulations allows the production of films for packaging and biomedical applications.

Evaluation of carboxylic acids as sustainable compatibilizing agents on blend sheets properties based on thermoplastic babassu starch and polypropylene

Polypropylene/babassu thermoplastic starch (PP/TPS, 70:30 w/w) blend sheets were prepared as an alternative material to use in disposable packaging, reducing the negative environmental impact of synthetic polymer. Three different carboxyl acids: palmitic (PP/TPS/P), citric (PP/TPS/C), and stearic (PP/TPS/S), were used as natural compatibilizing agents (NCA) and compared to the conventional synthetic maleic anhydride (PP/TPS/M), concerning mechanical, physical, crystallinity, and morphological properties of the blend sheets. The blend sheets without or with compatibilizing agents resulted in dark coloration, higher opacity, higher thickness, lower resistance to break, flexibility and rigidity, higher moisture, solubility in water, hydrophilicity, lower crystallinity, and more heterogeneous morphology in comparison to PP sheets. The presence of compatibilizing agents was observed to improve the mechanical and physical properties of the blend sheets, resulting in materials stronger and less hydrophilic. The citric acid was able to act similarly to the synthetic maleic anhydride, resulting in blend sheets with similar mechanical and physical properties. Finally, this work shows that the natural compatibilizing agent citric acid was analogous to the commercial one, synthetic maleic anhydride, bringing a more sustainable alternative. In addition, this work allowed assessing a new source of starch and offering one more alternative for applying this source to the plastic packaging sector.

Characterization, biodegradation and cytotoxicity of thermoplastic starch and ethylene-vinyl alcohol copolymer blends

Ethylene-vinyl alcohol samples containing 27 and 38 % ethylene were used to prepare blends containing 30 and 50 % thermoplastic starch (TPS) plasticized with glycerol. Their biodegradability and cytotoxicity were studied by different techniques (XRD, DSC, TGA, CA, ATR-FTIR, SEM). TPS presence significantly affected copolymer behavior, as confirmed by the appearance of OH IR 1000–1170 cm−1 bands and overall reduction of EVOH crystallinity, melting point, thermal stability and hydrophobicity. Biodegradation was more efficient in the presence of TPS and resulted in the formation of a robust biofilm by a consortium of three bacteria. A lower ethylene content facilitated biodegradation, making the material easier to metabolize. The mineralization percentages obtained after a 40-day bioassay at 45 °C were up to 66 % (EVOH-27/TPS 50:50). In vitro cytotoxicity assay demonstrated no cytotoxicity before and after biodegradation. EVOH/TPS blends are presented as a potential environmentally friendly alternative to pure synthetic polymers.

Biodegradable blends of thermoplastic waxy starch and poly(ε-caprolactone) obtained by high shear extrusion: Rheological, mechanical, morphological and thermal properties

The aim of this work was to develop polymer blends of plasticized thermoplastic waxy starch (TPS) and poly(ɛ-caprolactone) (PCL) using the largest amount of TPS possible to obtain a biodegradable material motivated by sustainability issues and to replace petrochemical-based polymers with alternatives based on biopolymers. Addition of TPS to other polymers has been used to obtain cheaper and increasingly biodegradable final products. However, TPS presents limited mechanical properties, and mixing with other polymers such as PCL is necessary to overcome these limitations and improve its processability. TPS was processed by extrusion and thermo-compression using 30 wt% glycerol. The blends were suitably processed by extrusion and further injected. The TPS/PCL blends were studied by varying the amount of PCL in a range of 10 wt% in increasing order of addition. Thermal analysis showed that introducing PCL in TPS increased Tonset because of the higher thermal stability of the former, and that the obtained blends presented a behavior intermediate to that of neat polymers.Graphical Abstract

Poly(lactic acid)/thermoplastic cassava starch blends filled with duckweed biomass

Duckweed (DW) is a highly small, free-floating aquatic plant. It grows and reproduces rapidly, comprises mainly protein and carbohydrate, and has substantial potential as a feedstock to produce bioplastics due to its renewability and having very little impact on the food chain. The aim of this work was to analyze the effect of DW biomass on the characteristics and properties of bio-based and biodegradable plastics based on a poly(lactic acid)/thermoplastic cassava starch (PLA/TPS) blend. Various amounts of DW biomass were compounded with PLA and TPS in a twin-screw extruder and then converted into dumbbell-shaped specimens using an injection molding machine. The obtained PLA/TPS blends filled with DW biomass exhibited a lower melt flow ability, higher moisture content, and increased surface hydrophilicity than the neat PLA/TPS blend. Incorporation of DW with low concentrations of 2.3 and 4.6 wt% increased the tensile strength, Young's modulus, and hardness of the PLA/TPS blend. Moisture and glycerol from DW and TPS played important roles in reducing the Tg, Tcc, Tm, and Td of PLA in the blends. The current work demonstrated that DW could be used as a biofiller for PLA/TPS blends, and the resulting PLA/TPS blends filled with DW biomass have potential in manufacturing injection-molded articles for sustainable, biodegradable, and short-term use.

Biodegradability and nutrients release of thermoplastic starch and poly (ε-caprolactone) blends for agricultural uses

Driven by the environmental stress caused by plastics, the interest on eco-friendly polymers has attracted the attention of researchers and industry. Thermoplastic starch (TPS) and poly (ε-caprolactone) (PCL) blends are good examples of sustainable material, exhibiting synergism between economic viability and properties. However, its biodegradability aligned to nutrients release has been less explored in agricultural applications. Herein, it is proposed the investigation of biodegradability of urea plasticized TPS and PCL blends, compatibilized with PCL grafted with maleic anhydride (PCL-g-MA), aiming fertilizers and sustainable agricultural products. The blends were prepared in a twin-screw extruder using a flat film die. The mechanical, thermal, morphological, and physical properties of TPS-PCL films were characterized, including biodegradation analysis via Bartha respirometer and nitrogen release in the soil. The films presented biodegradability and nitrogen release as a function of TPS content on blends formulation, presenting flexibility and robust mechanical properties. These findings may open a way of multifunctional agricultural products applied as fertilizer materials through economical and sustainable mulching films.

High Loading Degradation of Poly(lactide)/Thermoplastic Starch Blend Film Using Mixed-Enzymes Produced by Fed-Batch Culture of Laceyella sacchari LP175

High Loading Degradation of Poly(lactide)/Thermoplastic Starch Blend Film Using Mixed-Enzymes Produced by Fed-Batch Culture of Laceyella sacchari LP175

Influence of LLDPE-g-MA on Mechanical Properties, Degradation Performance and Water Absorption of Thermoplastic Sago Starch Blends

The addition of LLDPE-g-MA into the compound of sago starch/LLDPE was studied to improve its mechanical, morphology, degradation performance, and water absorption properties. Thermoplastic Sago Starch was composed of a mixture of sago starch and glycerol. LLDPE-g-MA was prepared in varied concentrations based on the weight of TPSS (0, 6, 8, 10, and 14 wt.%) by reacting LLDPE, maleic anhydride, and benzoyl peroxide using an internal mixer. The results showed an increase in values obtained from mechanical tests, i.e., tensile strength was improved from 0.6902 to 3.6187 N/mm2 with the addition of LLDPE-g-MA at 10 wt.%. The addition also resulted in a 1.44% increment in elongation at break and 251 N/mm2 for Young's Modulus. The surface morphology of the sample demonstrated an excellent interfacial adhesion reaction or LLDPE dispersion over the entire surface of the matrix (starch). The water absorption test continued to decrease with the increase in the LLDPE-g-MA concentration from 53 wt.% (without LLDPE-g-MA) to 14 wt.% at 10 wt.% LLDPE-g-MA concentration. The degradation performance showed that the sample could be degraded under all three conditions for up to 30 days.

Compatibilization of PLA grafted maleic anhydrate through blending of thermoplastic starch (TPS) and nanoclay nanocomposites for the reduction of gas permeability

ABSTRACT Here, the effects of compatibilization and clay nanoparticles on the gas permeability of nanocomposites of poly-lactic acid (PLA)/thermoplastic starch (TPS)/nanoclay were discussed. TPS and compatibilized PLA/TPS were tailored in the first step. The starch with D-sorbitol as a plasticizer was mingled through the internal mixer. Afterward, the maleination method was utilized on PLA to ameliorate the compatibilization of PLA and TPS. In this regard, maleic anhydrate (MA) has been grafted on PLA in the presence of L101 as a peroxide initiator via melt mixing to obtain PLA-g-MA. The optimum content of PLA-g-MA was about 4 phr, confirmed by DMTA and SEM. Noteworthy, the presence of PLA-g-MA has moderately improved the oxygen barrier. Then, the nanocomposites of PLA and TPS containing 1% of Cloisite-30B as well as the optimum compatibilizer (4phr), were produced by melt mixing in the masterbatch module leading to the formation of an extraordinary well-dispersed structure according to XRD patterns. The mixing order controlled the localization of nanosheets. It was concluded that the inclusion of 1% nanoclay in the PLA phase reduces the oxygen permeability by 55% compared to the pristine blend due to the tortuosity effect of nanosheets that are appropriately dispersed in the matrix.

Effects of Modified Thermoplastic Starch on Crystallization Kinetics and Barrier Properties of PLA.

This study reports on using reactive extrusion (REX) modified thermoplastic starch particles as a bio-based and biodegradable nucleating agent to increase the rate of crystallization, percent crystallinity and improve oxygen barrier properties while maintaining the biodegradability of PLA. Reactive blends of maleated thermoplastic starch (MTPS) and PLA were prepared using a ZSK-30 twin-screw extruder; 80% glycerol was grafted on the starch during the preparation of MTPS as determined by soxhlet extraction with acetone. The crystallinity of PLA was found to increase from 7.7% to 28.6% with 5% MTPS. The crystallization temperature of PLA reduced from 113 °C to 103 °C. Avrami analysis of the blends showed that the crystallization rate increased 98-fold and t1/2 was reduced drastically from 20 min to <1 min with the addition of 5% MTPS compared to neat PLA. Observation from POM confirmed that the presence of MTPS in the PLA matrix significantly increased the rate of formation and density of spherulites. Oxygen and water vapor permeabilities of the solvent-casted PLA/MTPS films were reduced by 33 and 19% respectively over neat PLA without causing any detrimental impacts on the mechanical properties (α = 0.05). The addition of MTPS to PLA did not impact the biodegradation of PLA in an aqueous environment.

Sericin cocoon bio-compatibilizer for reactive blending of thermoplastic cassava starch

Cassava starch was blended with glycerol to prepare thermoplastic starch (TPS). Thermoplastic starch was premixed with sericin (TPSS) by solution mixing and then melt-blended with polyethylene grafted maleic anhydride (PEMAH). The effect of sericin on the mechanical properties, morphology, thermal properties, rheology, and reaction mechanism was investigated. The tensile strength and elongation at break of the TPSS10/PEMAH blend were improved to 12.2 MPa and 100.4%, respectively. The TPS/PEMAH morphology presented polyethylene grafted maleic anhydride particles (2 μm) dispersed in the thermoplastic starch matrix, which decreased in size to approximately 200 nm when 5% sericin was used. The melting temperature of polyethylene grafted maleic anhydride (121 °C) decreased to 111 °C because of the small crystal size of the polyethylene grafted maleic anhydride phase. The viscosity of TPS/PEMAH increased with increasing sericin content because of the chain extension. Fourier-transform infrared spectroscopy confirmed the reaction between the amino groups of sericin and the maleic anhydride groups of polyethylene grafted maleic anhydride. This reaction reduced the interfacial tension between thermoplastic starch and polyethylene grafted maleic anhydride, which improved the compatibility, mechanical properties, and morphology of the blend.

Effects of nisin and EDTA on morphology and properties of thermoplastic starch and PBAT biodegradable films for meat packaging

Biodegradable active packaging was produced by compounding nisin (3, 6 and 9%) and nisin-ethylenediaminetetraacetic acid (EDTA) (3 and 6%) mixtures with poly(butylene adipate terephthalate) and thermoplastic starch blends (PBAT/TPS) by blown-film extrusion. Nisin and EDTA interacted with polymers, involving CO stretching of ester bonds and increased compatibility. This plasticized the films and modified the crystallinity, surface roughness and thermal relaxation behavior. Barrier properties were improved due to modified hydrophilic-hydrophobic properties, compact structures and crystallites that restricted vapor and oxygen permeation. PBAT/TPS films containing EDTA and nisin effectively inhibited lipid degradation in pork tissues corresponding with stabilizing the CO ester bond of triacylglycerol. Microbial growth was also inhibited, particularly in EDTA-containing films up to 1.4 log. Inactivation of microorganisms stabilized redness and delayed meat discoloration, preserving the quality of packaged pork. Interaction between nisin, EDTA and polymers modified the morphology and film properties and functionalized biodegradable food packaging to inactivate microorganisms.

Effect of Different Molecular Weight of PEG on the Crystallization Behaviors of Binary Polymer Blends PLA/TPS

Serial poly (lactic acid) (PLA) and thermoplastic starch (TPS) blends (with a fixed content of 20 wt.% TPS) were prepared by melt extrusion process. The effect of different molecular weight of PEG on the thermal and rheological properties of PLA/TPS blends was studied by the melt flow rate (MFR) and DSC analysis. The results showed that the molecular weight of PEG influenced the miscibility and crystallization behavior of PLA/TPS blends. Blend added with PEG400 showed a single Tg, and blends with PEG600 provided remarkable improvement of rheological properties with an increase in flow rate to 49.02 g/10 min. 4% content of poly (ethylene glycol) (PEG) can positively contribute to improve crystallization rate of PLA by reducing the melting temperature and cold crystallization temperature.